The reaction between cyanide ions and alkyl halides is a well-known and convenient method for the preparation of nitriles. Primarily, benzylic and alkylic halides are known to give acceptable yields of nitrile when the reaction is carried out under the proper conditions, i.e., using relatively high temperatures and polar solvents. See, for example, Freidrich et al., in Rappoport, "The Chemistry of the Cyano Group", pp. 87-86, Interscience, New York, N.Y., 1970. However, since the cyanide ion is one of the stronger bases, olefin formation (and concurrent dimerizations and polymerizations) are unavoidable.
While a great deal of research has provided numerous examples where ultrasound (sound waves whose frequencies lie within the range of 20 to 10,000 kHz) has been used to activate metal surfaces, the literature does provide a limited number of examples where inorganic bases can be used under heterogeneous conditions in organic reactions.
Shibata et al. have described the cyanomethylation of a variety of chalcones by the Michael addition of the radical anion derived from acetonitrile. Sonolysis for about fifteen minutes in the presence of potassium peroxide produced the desired nitrile. See Shibata et al., Chem. Lett., 519 (1987). Other sonochemical methods permit the use of cyanides of various metals to lengthen the carbon chain by one unit under extremely simple conditions. Acyl cyanide, for example, is readily prepared at low temperatures using potassium cyanide under ultrasonic conditions. Conventional methods require copper, silver or thallium salts. Ando et al., Synthesis, 637 (1983).
There remains a need to develop a method for preparing substantially pure, simple nitriles in a single step with few competing reactions.